The invention relates to an automatic welding assembly for welding together adjacent pipes, at a joint therebetween, of a generally horizontally disposed pipeline. There are a number of prior art devices for welding together adjacent pipes of a pipeline, however, such prior art devices are not automatic, but are rather semi-automatic and must either be disassembled for movement to a new position or otherwise manually moved into a different position once one welding operation is completed. Such prior art devices are generally useful for welding together pipes of the same diameter, however, no provision is made therein for welding transitions of pipes of different diameter, nor for accommodating pipes all of the same diameter, but of a size different than a single design size of the device. Such prior art devices also do not provide for making of a complete weld at each joint between pipes by revolving a welding nozzle around the joint a plurality of times, each time with a different welding pattern of the nozzle taking place, nor do the prior art devices provide as positive of a means for supporting the rotation of a welding nozzle with respect to the pipes to be welded. Typical prior art devices, having one or more of the above-mentioned drawbacks, are disclosed in U.S. Pat. Nos. 3,084,244, 3,256,418, 3,681,560, 3,681,564, 3,702,913, 3,777,103 and 3,783,222.
The welding assembly according to the present invention includes a welding nozzle and associated apparatus, means for mounting the welding nozzle for revolution around pipes to be welded, the nozzle being disposed adjacent the joint between the pipes to be welded together, means for supporting the mounting means for movement along the length of the pipe from one joint to the other, means for powering the supporting means to provide for automatic movement from one position to the next, and means for adapting the supporting means to transitions and pipes of different diameter as the assembly is automatically moved from one welding position to the next. The mounting means for the welding nozzle and associated apparatus includes a pair of rings encircling the pipes, each ring having an upper gear-toothed surface thereof concentric with the pipes, and a lower gear-toothed surface thereof concentric with the pipes and disposed closer to the pipes than the upper surface. Means are provided for horizontally spacing the rings from each other. A plurality of planetary gear sets may be associated with each ring in operative engagement with the gear-toothed surfaces thereof, each planetary gear set including three circular gears, two in engagement with one gear-toothed surface, and the other in engagement with the other gear-toothed surface, and an idler disposed between the circular gears and in operative engagement with each of them. Alignment means are disposed between the circular gears to insure proper alignment therebetween, and at least one of the circular gears is powered by a motor associated with the welding nozzle and associated apparatus.
The welding nozzle is supplied with welding wire from a spool which is automatically driven to provide the correct amount thereto, and means are provided for oscillating the welding nozzle in a particular oscillator path during a welding pass. A feeler precedes the welding nozzle during its movement around the pipes, and senses the weld in the joint to change the oscillatory path of the welding nozzle at the start of each pass. Preferably three passes are made at each point, a root pass, an overlap pass, and a wash pass. When all the passes are completed, the assembly is ready to move on to the next joint. Means are provided for moving the welding nozzle radially so that it is always is proper position for welding.
Each of the supporting means for the mounting means includes a plurality of rotatable rod members operatively connected to one of the mounting rings, a wheel assembly connected to one end of the rod members for engagement with the exterior surface of the pipes, motor means for rotating the rod members, means for transforming rotary movement of the rod members into radial movement of the wheel assemblies with respect to the rings, and feeler means associated with each wheel assembly for automatically controlling the rotation of the rod members to automatically adapt the welding assembly to pipes of different diameters. At least one wheel assembly associated with each ring is driven by a motor mounted therewith.
It is the primary object of the present invention to provide an improved welding assembly that automatically moves from one joint to the next for welding pipes of a pipeline, and which can adapt to pipes of different diameter and which can make a permanent weld at each joint. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.